The present invention relates generally to analysis of dimensioned drawings and particularly to dimension analysis of computer generated drawings.
In a typical Computer Aided Design (CAD) system a user generates a drawing by explicit specification of geometric entities in terms of cartesian coordinates. The user must accurately construct the drawing so as to uniquely define its geometry. In a dimension driven CAD system, the user first establishes the topologic aspects of the drawing and subsequently imposes dimension constraints. A scale drawing is generated by dimension analysis of the topologic structure and dimension constraints imposed thereon. Some dimension driven CAD systems model the drawing as a set of equations and solve the equations on a strictly numerical basis but such systems are time consuming and provide little meaningful error information to the user. According to other dimension driven methods, the user specifies a particular order of construction, i.e. an explicit sequential application of constraints or geometric operations, so as to accomplish a unique geometry in light of an ordered set of dimension constraints. This method requires the user to think in cumbersome geometric terms not directly related to the task of generating a drawing. It is desirable for a dimension driven CAD system to determine efficiently when a set of dimension constraints uniquely and consistently defines the drawing geometry.